Electro-mechanical beauty chair



June 20, 1961 H. F. NEWMAN ELECTRO-MECHANICAL BEAUTY CHAIR 5 Sheets-Sheet 1 Filed Dec. 5, 1957 Harvard F. Newman June 20, 1961 H. F. NEWMAN ELECTRO-MECHANICAL BEAUTY CHAIR 5 Sheets-Sheet 2 Filed Dec. 5, 1957 Iavanimr Howard F Newman June 20,. 1961 H. F. NEWMAN ELECTRO-MECHANICAL BEAUTY CHAIR .5 Sheets-Sheet 3 Filed DeG. 3, 1957 M Z a 0 5 Howard F Newman June 20, 1961 H. F. NEWMAN ELECTRO-MECHANICAL BEAUTY CHAIR 5 Sheets-Sheet 4 Filed Dec. 5, 1957 NU NWN QWN Ban-Zap Howard F lVcn/man June 20, 1961 H. F. NEWMAN ELECTRO-MECHANICAL BEAUTY CHAIR 5 Sheets-Sheet 5 Filed Dec. 5, 1957 .E'Eflffll" Howard F. Newman United States Patent 9. a ELEClRO-MECHANICAL BEAUTY CHAIR Howard F. Newman, Chicago, 111., assignor to Emil J. Paidar Company, Chicago, 111., a corporation of Illinois Filed Dec. 3, 1957, Ser. No. 700,341 5 Claims. (Cl. 155-93) The present invention relates to an improved power lift for a chair, and more specifically to a power lift employing a direct mechanical drive between a chair and a base for the chair with the lift being driven by an electrical motor.

An object of the invention is to provide an improve power lift mechanism whereby an operator may selective- 1y control the elevation of a supported device, wherein an overall basic lift mechanism is provided which may be used in barber chairs, beauty chairs, optometrists instrument tables and the like device which are used at various controllable elevations.

Another object of the invention is to provide an improved power chair lift which utilizes a direct mechanical drive between an electrical driving motor and the chair eliminating the expense and complex mechanism necessary for other types of lifts, such as those employing hydraulic pressure.

A further object of the invention is to provide an improved chair power lift utilizing a threaded screw with a ball nut with power means for driving the screw and nut in relative rotation.

An important object of the invention is the provision of a mechanical lift for a chair employing a screw and a ball nut driven by a high speed motor wherein the problems of noise are greatly reduced, and wherein the excitation of the driving members is insulated from other parts which might tendto resonate at the driving frequencies, and the lift may be used in locations where operational noise would be oifensive and objectionable.

A still further object of the invention is to provide an improved ball nut lift mechanism for a chair wherein the relative operating parts are insulated from each other with respect to vibrations and noise, and wherein the natural frequency of the-parts is removed'from the frequency of the driving and operating parts.

Another object of the invention is to provide improved means for the ball nut and screw wherebythe nut will be automatically stopped when it reaches the end of the screw, but will not jam.

Still another object of the invention is to provide an improved resilient support for a chair to be employed in a power driven rotary screw lift.

Afurther object of the invention is to provide an improved ball nut construction for use in combination with a chair elevation mechanism which will result in improved operation and reduction of noise.

A still further object of the invention is'to provide a manually operated control for regulating and selectively controlling the elevation of the chair, wherein the control is accessible from any location to the operator around the chair.

A further object is to provide an' improved manually operated control for a mechanically power-driven chair lift which is foot operated and reduces the eifort which must be exerted by the operator, and enables the operator to quickly andeasily locate the control, and to operate it with greater precision without excessive muscular strain or skill.

Other objects and advantages will become more apparent with the teaching of the principles of the inventive concepts of the invention in connection with the disclosure of the preferred embodiments thereof in the specification, claims and drawings, in which:

FIGURE 1 is a perspective view of a power-elevated Patented June 20, 1961 chair employing a power lift embodying the principles of the present invention;

FIGURE 2 is an enlarged vertical elevational view of .the power lift mechanism with parts broken away for FIGURE 8 is a plan view of the chair base;

FIGURE 9 is a vertical sectional view taken through the base of a chair embodying an alternative construction of the invention;

FIGURE 10 is a plan view taken from a direction looking upwardly at the bottom of the chair to illustrate the location and mounting of aswitch control ring and foot positioning ring; and,

FIGURE 11 is a detailed elevational view with parts broken away to illustrate the arrangement of bearings in oneform of the ball nut.

While the features of the invention are susceptible to use'in various environments, they are shown in their preferred form as embodied in a power driven lift, which is shown by way of illustration as adapted to controlling the elevation of a beautychair. It will be understood that the features of the invention may be used in other arrangements making use of the inherent advantages and objectives of the invention.

As illustrated in FIGURE 1, a chair 10 is supported in a position to receive an occupant above a base'12. The chair is provided with the usual seat 14 and back 16, and with arm rests 18 and 20. A foot rest 22 may also be provided.

The chair 10 is thus illustrated, may be utilized as a beauty chair in a beauty parlor where the operator attends to the occupant in the chair, and adjusts the elevation of the chair for optium efiiciency in height.

The elevation of the chair is controlled by a power lift mechanism 24 which is shown in detail in FIGURES 2. and 3. The power lift mechanism 24 is driven by an electric motor 26, which is supplied electricity through a suitable circuit, not shown, and controlled by an electrical switch, also not shown. The switchis conveniently controlled by the operator stepping on a control ring 28, which is shown in FIGURE 1. The. control ring. 28 extends approximately 180 around the chair base,.as shown in FIGURE 1, and is supported-at its ends on the legs 30 and 32 of the base 12. The ring is carried by a pivotal support means within the legs 30 and 32 and extends through a notch 34 in an intermediate leg 36. The operator can thus start the motor at'will by touching her foot to the ring 28, and depressing it. 7

The motor 26 is reversible, and various switching arrangements can be utilized for enabling the operator to control the direction of rotation of the motor, suchas by lifting on the ring for rotation in one direction, and depressing the ring for rotation in the opposite, direction.

The base 12 is shown having four legs extending from a central hub 38 with the legs extending radially and being circumferentially spaced apart. The chair will normally be positioned with the legs 30, 32- and 36 located so as to'mak'e the switch operating ring 28'accessible to the operator. The remaining leg 40 is con- 3 structed hollow and sufliciently large so as to house the motor 26 in the position shown in FIGURE 8. The base 12 may be constructed of formed metal, and is coated on the inside with a layer of insulation 42 to absorb the operation sound of the motor 26, and to reduce the vibrations of the base to thereby considerably reduce the noise level. The motor is preferably of the high speed type so as to obtain the power necessary without providing considerable space and to reduce the cost of manufacture. With the high speed motor, the problem of noise becomes an important factor, and the present invention contemplates reducing the vibrational and operational noise of the mechanism, which is caused by the motor and by the lift mechanism, as will be described.

As illustrated in FIGURES 2 and 3, the chair is supported above the base 12 on a vertical tube 44, which has rigidly secured to its top end, a chair supporting plate 46. The plate is provided with holes 48 for bolting the chair thereto.

The tube 44 and chair supporting plate 46 are elevated and lowered with the chair by the power lift mechanism 24 which includes an elongated rotating threaded screw 50 and a mating coacting ball nut 52.

The ball nut 52 is of the usual type having a housing 54 with ball bearings contained therein to be held between the grooves on the inside of the nut and the helical grooves 56 formed by the threads in the screw 50. The balls within the ball nut housing 54 are contained therein by a cap 58 held in place by bolts 60. The balls may be formed of steel, or as illustrated in FIGURE 11, may be alternately of steel and nylon.

FIGURE 11 illustrates the ball nut with portions broken away. A nut 47 has internal thread grooves 49 and surrounds a screw 51 with thread grooves 53. The balls 55 and 57 are located in the grooves and balls 57 are formed of a metal, such as steel, and the intermediate balls 59 are formed of nylon. This arrangement obtains long wear and substantially decreases the noise of operation.

For elevating the chair, the screw 50 is rotated by the electrical motor 26 driving the screw through a worm gear assembly 62. The motor is supported on the housing for the worm gear assembly 62 by bolts 64, which extend through a bracket 66 and which carry rubber bushings 68 for isolating the vibration of the motor from the worm gear housing. The motor shaft 70 drives a worm, not shown, within the housing and is secured to rotate the screw 50. Since the motor 26 is reversible, the screw can be turned in either direction, depending upon the direction in which the motor is operated.

As the screw is rotated in the elevating direction, the ball nut 52 rides up the screw, lifting the tube 44 and the chair supporting plate 46. The tube 44 is supported on the ball nut in a resilient manner to resiliently support the chair and to insulate the tube 44 and chair from vibrations of the nut traveling along the screw, and vibrations received from the motor.

As is illustrated in FIGURE 3, the ball nut housing 54 is provided with a shoulder 72 at its upper end on which seats an annular supporting ring 74. The annular sup porting ring 74 carries a rubber thrust ring 76. On the top of the rubber thrust ring is a nylon thrust washer 78,

and a tube supporting cup 80 seats in an inverted position, on the top of the nylon thrust washer 78.

The tube 44 is secured to the cup 80 so that as the chair rotates and the tube 44 rotates therewith, the inverted cup 80 will slide on top of the nylon thrust washer. The nylon washer provides a smooth bearing surface for ease of rotation of the chair.

To maintain the resilient support assembly as a unit, a snap ring 82 fits into a groove 84 within the inner surface of the cup 80, and the snap ring 82 projects beneath the annular ring 74, which seats on top of the ball nut housing 54. Thus the snap ring 82 holds the supporting ring 74, the rubber thrust ring 76 and the nylon thrust washer 78 within the inverted cup 80, and prevents the cup from being lifted upwardly off these members. A snap ring 83 fits into a groove on the collar 85 of the ball nut assembly to prevent the tube 44 and its associated mechanism from being lifted upwardly to separate from the ball nut 52.

In order to cause the ball nut 52 to travel along the screw 50, as the screw rotates, the ball nut is held against rotation by a rotation-preventing pin 86, FIGURE 2, which is made integral with the lower bolt 60. The pin 86 carries a roller 88 at its outer end, and this roller rides in a groove 90, FIGURE 5. The groove 90 is formed by a pair of vertical ribs or rails 92 secured to the inside of a shell 94 which encloses the tube 44 and the screw 50. The shell is cylindrical in shape and is secured at its base to the hub 38 of the base 12. This, of course, makes it non-rotational with respect to the base, and it is capable of holding the ball nut against rotation.

In some instances it may be preferred to omit the pin 86 and groove 90. In these constructions the nut is prevented from rotating by the friction between the surfaces of the rubber thrust rung 76 and the nylon washers 74 and 78 and the cup 80 and washer 78. 74 is held substantially non-rotational by the lock ring 83.

When the nut 52 reaches its upper limit of travel, it is stopped by the rubber washer 126. When the nut reaches its lower limit of travel, it is stopped by the stacked washers 110, 112 and 114. When these limits are reached, the nut will rotate with the screw. When the screw is reversed, the nut will break from the stop and again travel along the screw. The washer and ring assembly of the members 76, 78 and 80 which act as a thrust bearing, have a friction-resistance torque of at least as great as the torque on the nut driving rotation of the screw.

At its upper end, the shell 94 is secured to a collar 96 which controls the resistance to rotation of the chair. The collar 96 is annular in shape, as shown in FIGURES 2, 3 and 4, and is split, as indicated by a gap 98. A thumb screw 100 extends across the gap, and is threaded into the collar at one side to draw the gap together and clamp the collar against the tube 44. Within the collar is a split nylon bearing 102 which provides a bearing surface between the collar 96 and the chair supporting tube 44, FIG. 4.

As the thumb screw 100 is tightened, the nylon bearing 102 will be clamped tighter against the tube 44 to increase the resistance to rotation of the chair. Since the collar 96 is held at the top of the shell 94, the collar 96 is locked in position with respect to the base 12. If the chair is to be completely locked against rotation, the thumb screw 100 is drawn tight to clamp the collar 96 tightly around the tube 44. This arrangement positively and securely holds the chair to the desired resistance against rotation, and there is no play present which would permit wobble of the chair. This is important for use such as a beauty chair, wherein a torque is created, such as by the operator combing the occupants hair in a direction normal to the axis of the chair.

If the screw 50 is rotated continuously in either direction, the ball nut will reach the end of the screw. Stops are provided to prevent the nut from traveling oif the end of the screw. These stops are constructed so as to prevent jamming in a manner whereby the motor cannot be reversed to run the screw in the opposite direction.

When the screw is rotated in a direction to elevate the chair to the maximum height, a nylon jam ring 104, FIG- URES 2 and 3, will engage the lower surface 106 of the collar 96. The jam ring 104 is carried on the top surface of the support cup 80, carrying the tube 44. The slippery Nylon washer sufficiently far to jam the ring 104 against the base of the collar 96.

When the chair is lowered to its lowest position, the lower surface 108 of the ball nut 52 will engage a stack of stop rings including a nylon ring 110, located between upper and lower steel rings 112 and 114. These rings rest on the top surface 116 of the housing 63 for the worm gear assembly 62. Again the slippery nylon ring 110 will prevent the mechanism from jamming, and the motor can be reversed.

In some instances, a very heavy occupant may be seated in the chair to cause an undue strain on the motor 26 as it starts elevation. To prevent stalling the motor and decrease the load on the lift mechanism, a secondary support means is provided. This secondary support includes a nylon supporting ring 118 resting on the upper surface 120 of the collar 96. The nylon ring is engaged by the lower surface 122 of the support plate 46.

As the occupant is seated in the chair, his weight will press down on the tube 44 to compress the rubber thrust ring 76. Uunder the weight of. a normal occppant, the thrust ring is partially compressed, and with a very heavy occupant seated in the chair, the ring is sufliciently compressed to cause the lower surface 122 of the plate 46 to rest on the nylon ring 118. The nylon ring thus forms a secondarysupport for the chair and occupant; The ring will also act as a bearing in the event the chair is rotated in this position. The rubber thrust ring 76. has Sulficient space to expand laterally with excessive compression, inasmuch as the lateral space between it and the cup 80 is. sufliciently large to permit expansion.

Thus, the weight of the occupant in the chair will be partially supported on the collar 96 and transmitted through the shell 94 directly to the base, and will not be wholly carried on the ball nut 5'2. This will prevent the motor from stalling with an extreme starting load such as might be encountered if the full weight of the occupant were permitted to rest on the nut. Once the motor has started, it will be able to continue operation to raise the support plate 46 off the secondary support means supplied by the collar 96.

It will be noted that the rubber thrust ring 76 provides avibration insulation between the tube 44 leading up to the seat and the ball nut 52 and screw 50. Since the rubber washer 76 is compressed during operation, this static deflection will improve its ability to isolate the vibrations of the ball nut assembly 54 from the tube 44.

Noise vibrations are prevented from being transmitted from the screw 50 by the construction of the upper end of the screw. At the upper end, the diameter of the screw is reduced; to provide a projecting end 124 which is cylindrical in shape, and which receives a cylindrically shaped rubber washer 126. The washer is compressed axially and held in place by a metal washer 128 secured by a retaining ring 130, which is snapped in a groove on the end 124; FIGURE 7.

The rubber washer 126 is also compressed radially by a nylon compressing ring 132. The ring 132 has a smaller diameter than the normal diameter of the rubber washer126, and holdit in radial'compression. The nylon ring 132iis of a size to smoothly slide within the inner cylindrical surface 134, FIGURE 2, of the tube 44. The nylon ring 132 thus provides a hearing which is resiliently supported on the precompressed rubber washer 126.

This'provides sound insulation between the tube and the screw, and inasmuch as the rubber is compressed, its ability to isolate vibrations of the screw 50 from the tube is improved.

Within the base 12, the entire power lift assembly 24,

v is supported to prevent the transmission of noise generating-vibrations-to the hollow base. Asshown in FIGURE 6, a hanger 13-6 is secured within the hub '38 of the hollow base. This hanger is provided with spaced sides 138 and 140, which have circular openings 142. and 144.

Positioned within the circular openings are sound insulat ing cylinders 146 and 148; 1

The sound insulating cylinders are identical incon struction, and therefore, only the cylinder 146 need be described in detail. The cylinder 146 has an outer cylin drical hollow metal shell 150 enclosing a rubber tube 150 therein. Within the'tube is another metal tube 152 with the diameters of the tube 152 and the outer shell 150 being such that the rubber tube 150 is compressed. This compression of the rubber tube 150will substantially improve its ability to isolate vibrations of the base 159 of the gearbox of the worm gear assembly 62 from the hanger 140.

The lift mechanism 24 is supported on the hanger 140 by a bolt 154 extending through the center of the cylinders 146 and 148 and projecting through a hole in the downwardly extending base 159 of the worm gear assembly 62. The bolt 154 supports the insulating cylinders 146 and 148 which are located against the sides 160 and 162 of the worm gear base 159.

In operation of the chair, an occupant is seated therein whereupon the weight of the chair is transmitted to the supporting plate 46 and to the tube 44, FIGURES 2-and 3. The rubber washer 76 compresses which improves its vibration absorbing ability and thus prevents the transmission of noise generating vibrations. In the event the occupant is extremely heavy, the rubber washer will compress to a degree whereupon the plate 46 will settle down upon the secondary support means including the nylon washer 118 resting on the upper surface 120 of the collar 96. This reduces the pressure between the ball nut 52 and the screw 50, and will prevent the motor from stalling and permit it to start.

To raise the chair occupant, the operator presses down upon the ring 28 to close a switch to the motor 26. The screw 50 is driven in rotation through the motor 26 driving the worm gear drive '62. The motor may be stopped at the desired elevation, or if rotation of the screw is continued, the jam washer 104 will engage the lower surface 106 of the collar 96 to. provide a stop. The smooth slippery washer 104 will permit the motor to be reversed to again lower the chair, and at the lowerextreme of movement of the ball nut 52, the washers 112' and 11.4 with the nylon washer 110 therebetween will: provide a stop.

The ball nut and screw and the motor are isolated from the chair and base to prevent noise generating vibration from being transmitted. Insulation from the. base is caused by the noise insulating cylinders 146. and 148 shown in detail in FIGURE 6. Insulation between the nut 52 and the tube 44 is obtained through the rubber thrust washer 76. Insulation between the upper end. of the screw 50 and the tube 44, is obtained by theprecompressed rubber washer 128 and the nylon ring 132.

In the arrangement of FIGURES 9 and 10, which illustrate another embodiment of the invention similar in many respects to the embodiment shown in FIGURES 1 to 8, a base member is provided. A chair or the like is supported from a chair support 172, and power elevating mechanism extends between thechair support172and the base 170.

The power elevating mechanism includes a ball nut assembly 174 having a ball nut housing 176 with spherical ball bearings therein, and a threaded screw member 178 which passes through the ball nut housing 176. The screw member is driven in rotation, and is connected to a Worm gearing within a housing 180. The worm gearing is driven by a motor 182. This mechanism operates similarly to the mechanism of FIGURES 1 through8'.

As the screw 178 is driven in rotation, the ballnut housing 176 is raised thereon. To raise the chair support 172, a tube 184 extends upwardly from the ball nut housing and is connected to the chair support 172. This connectionis obtained by the tube beinginternally threaded 7 at its upper end 186 to receive a cap screw 188. The head 190 of the cap screw holds the support plate 172 firmly down on the top of the tube 184.

The tube is held upright and slides through a split collar 192 containing a nylon bushing 194, and provided with a cross-locking bolt 196.

The collar 192 is supported within a ring 198 at the top of a hollow cylinder or shell 200. This cylinder or shell is connected at its base to an outwardly extending supporting flange 202 for connecting it to the base 170. The base 170 has an upwardly extending annular necked portion 204 integral with the base for receiving the flange 202 which has a downwardly turned edge 206.

To prevent the ball nut housing 196 from rotating when the screw is driven, it has a radially projecting rotation-preventing pin 208 which rides against a rail 210. The rail 210 extends on one side of the pin 208 only, since the tendency of the ball nut will be to rotate in a single direction only.

The motor 182 and the ball nut assembly 174 which supports the chair are both supported within the hollow base on shaped metal straps 209 and 211 which are secured within the base, such as by bolts 212 and 214. The straps also support a switching mechanism 218 for controlling the motor 182.

The switch 218 is operated by the vertical up and down movement of a switch plate 220 supported by coil compression springs 222 on brackets 224. The plate 220 is moved by rods 226 and 228 which extend radially horizontally outwardly to connect to a switch operating controlring 230.

The control ring 230 extends annularly 360 around the chair base and is engaged and depressed by the operators foot for operating the motor 182 to elevate or lower the chair.

The switch 218 is of the type which when a movable switch arm is moved part way, a first pair of contacts are closed, and when moved a further amount, another set of contacts are closed. The first set of contacts operate the motor 182 in one direction, and the second set in a second direction to raise or lower the chair, depending on how far the switch ring 230 is pushed downwardly by the operators foot.

The switch plate 220 which controls the switch 218 is held upwardly by coil compression springs 222 which rest on a bracket 224 and surround pins 225, which resiliently support the plate. The plate is guided in vertical movement by pins 227 as it moves up and down. When the switch plate 220 is moved downwardly, a boss 229 pushes downwardly on a switch contact arm 231 on the switch bringing its contact into engagement with contact of switch arm 233. Additional downward movement of the switch plate 220, which is caused by pushing the control ring 230 further downwardly, opens the contacts between contact arm 233 and contact arm 2'35 and closes contacts between contact arm 233 and contact arm 237. The switch contact arms are supported at their base by terminal block 239. Operation of the contact arms in the aforedescribed manner operates the motor in either the forward or reverse direction.

In order that the operator may engage the control switch ring easily, a foot positioning ring 232 is positioned concentric with the control ring, and having a larger diameter so as to be spaced therefrom. The operator, thus, without looking, can slide her foot up against the positioning ring 232 and rest her foot thereon, bringing her toe downwardly against the control ring. Thus, she does not have to balance on one foot like a stork, and does not have to hunt for the control ring.

The positioning ring is supported on bolts 234, 236, 238, and 240 which thread upwardly into the base 170. As shown in FIGURE 9, coil springs 242 extend over the bolts and press downwardly on the ring 232 to hold it against a floor surface at the level of the flooras determined by supporting feet 244 and 246 for the base.

The base is supported and the chair is leveled by these supporting feet, as shown at 244 and 246, which are adjustably threaded up into the base. Also carried within the base is an electrical cord 248 which passes through a supporting block 250 in the base to terminate in a plug 258 for supplying electricity to the elevating and lowering motor.

The operation of the chair assembly in FIGURES 9 and 10 is, in most respects, similar to the assembly of FIGURES 1 to 8. For ease of operating the elevating and lowering assembly, the operator slides her foot up against the positioning ring 232, and brings her toe down into engagement with the control ring 230 to press it part way or full way down, depending upon the direction in which the motor 182 is to be operated, and whether the chair is to be elevated or lowered.

Thus, it will be seen that I have provided an improved power chair elevating mechanism and control therefor which meets the objectives and advantages hereinbefore set forth. The mechanism embodying the principles of the invention obtains a practical operative mechanical power lift, which avoids disadvantages heretofore present due to objectionable noise generation. The mechanism, therefore, presents a quite-operating, electrically operated mechanical device which can be inexpensively manufactured.

The device is positive in operation and takes advantage of the low frictional resistance of a ball nut mechanism. The invention is well suited to lift mechanisms for beauty chairs or barber chairs or the like, and is susceptible to adaptation for utilization in various environments.

I have, in the drawings and specification, presented a detailed disclosure of the preferred embodiment of my invention, and it is to be understood that I do not intend to limit the invention to the specific form disclosed, but intend to cover all modifications, changes alternative constructions and methods falling within the scope of the principles taught by my invention.

1 claim as my invention:

1. A power lift for a chair comprising a chair member, a base member for carrying the weight of the chair member and its occupant, an elevating mechanism including an elongated threaded screw element and a mating nut element adapted to travel axially along the screw element with relative rotation, a tube adapted for connection to one of said chair and base members with said screw element being connected to the other of said members and the tube being connected to said nut element, power means for driving the elements in relative rotation to raise the chair, a resilient collar around the screw element located between the screw and tube isolating the screw from the tube to prevent the transmission of vibrations, and means prestressing the collar and retaining the stress therein.

2. A power lift for a chair comprising a support member adapted for connection to a chair, a base for supporting the chair from a supporting surface, a chair elevating mechanism connected between the base and support member, power means for driving said elevating mechanism, a resilient vibration insulating support between the base and support member and insulating the elevating mechanism and supporting the weight of the chair and occupant, and a secondary support means for the chair support member responsive to compression of the resilient insulating support and operative automatically to provide support to the chair after the vibration insulating support has been compressed at predetermined amount.

'3. A power lift for a chair comprising a supporting member adapted for connection to a chair, a base supporting the chair from a supporting surface, a chair elevating mechanism connected between the base and support member, power means for driving said elevating mechanism, a resilient vibration insulating support between the elevating mechanism and support member and insulating the elevating mechanism and supporting the weight of the chair and occupant, and means for aiding in supporting the chair when the weight thereof has C0111- pressed the resilient support a predetermined amount including a surface on the elevating mechanism and a surface on the support member spaced to engage with compression of the resilient support.

4. A power lift for a chair comprising a support member adapted for attachment to a chair, a base for supporting the chair in an upright position, a screw and nut lift mechanism connected between the base and the support member for elevating the chair with relative rotation of the screw and nut and movement of the nut along the screw, power means for driving the screw and nut in relative rotation, a resilient support connected between the lift mechanism and support member, and secondary support means positioned to be engaged by said support member when the chair is in lowered position and when the resilient support is compressed whereby the load of the chair between the nut and screw is reduced for starting the power means to raise the chair, said secondary support being carried on the base.

5. In a power lift for a chair adapted to support an occupant at varying elevations having a base for supporting the chair from a supporting surface, a screw element and a ball-nut element matingly threaded thereto connected between the chair and base, power means for driving said screw element in relative rotation to adjust the height of the chair above the base, and having means for connecting said nut element non-rotatably to the base,

the combination comprising a tube surrounding the screw element and forming a housing therefor and rotatably resting on the nut element and non-rotatably connected to the chair to support the chair, and adjustable locking means connected between said base and said tube permitting relative rotation therebetween but adjustably varying resistance to rotation whereby the rotationable posi tion of the chair may be locked and the resistance to rotation of the chair may be increased.

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